The best way to tenderize round steak is to physically tenderize the round steak using a meat mallet.
The meat mallet is used to physically beat the round steak and break down the tough fibers in the meat which is the quickest way to tenderize the round steak.
Breaking down the tough meat fibers in the round steak helps to tenderize it.
Slicing the round steak against the grain and letting the round steak rest is also another good way to tenderize the round steak.
Or cooking the round steak slow and on low helps to tenderize the steak.
When you cook the round steak or other steaks slowly such as by simmering the steak or slow cooking the steak in a slow cooker helps to soften and tenderize the steak.
The slow cooking the steak or other tough meats helps to break the fibers up in the meat and helps the meat become soft.
The round steak is a beef steak from the "round", the rear leg of the cow.
Round Steak is divided into cuts including the eye round, bottom round, and top round, with or without the "round" bone, and may include the knuckle, depending on how the round is separated from the loin.